If the callchain is available, BPF program can use bpf_probe_read_kernel()
to fetch the callchain, or use it in a BPF helper.
Signed-off-by: Song Liu <songliubrav...@fb.com>
---
include/linux/perf_event.h | 5 -----
include/linux/trace_events.h | 5 +++++
include/uapi/linux/bpf_perf_event.h | 7 ++++++
kernel/bpf/btf.c | 5 +++++
kernel/trace/bpf_trace.c | 27 +++++++++++++++++++++++
tools/include/uapi/linux/bpf_perf_event.h | 8 +++++++
6 files changed, 52 insertions(+), 5 deletions(-)
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 00ab5efa38334..3a68c999f50d1 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -59,11 +59,6 @@ struct perf_guest_info_callbacks {
#include <linux/security.h>
#include <asm/local.h>
-struct perf_callchain_entry {
- __u64 nr;
- __u64 ip[]; /*
/proc/sys/kernel/perf_event_max_stack */
-};
-
struct perf_callchain_entry_ctx {
struct perf_callchain_entry *entry;
u32 max_stack;
diff --git a/include/linux/trace_events.h b/include/linux/trace_events.h
index 5c69433540494..8e1e88f40eef9 100644
--- a/include/linux/trace_events.h
+++ b/include/linux/trace_events.h
@@ -631,6 +631,7 @@ void bpf_put_raw_tracepoint(struct bpf_raw_event_map *btp);
int bpf_get_perf_event_info(const struct perf_event *event, u32 *prog_id,
u32 *fd_type, const char **buf,
u64 *probe_offset, u64 *probe_addr);
+int bpf_trace_init_btf_ids(struct btf *btf);
#else
static inline unsigned int trace_call_bpf(struct trace_event_call *call, void
*ctx)
{
@@ -672,6 +673,10 @@ static inline int bpf_get_perf_event_info(const struct
perf_event *event,
{
return -EOPNOTSUPP;
}
+int bpf_trace_init_btf_ids(struct btf *btf)
+{
+ return -EOPNOTSUPP;
+}
#endif
enum {
diff --git a/include/uapi/linux/bpf_perf_event.h
b/include/uapi/linux/bpf_perf_event.h
index eb1b9d21250c6..40f4df80ab4fa 100644
--- a/include/uapi/linux/bpf_perf_event.h
+++ b/include/uapi/linux/bpf_perf_event.h
@@ -9,11 +9,18 @@
#define _UAPI__LINUX_BPF_PERF_EVENT_H__
#include <asm/bpf_perf_event.h>
+#include <linux/bpf.h>
+
+struct perf_callchain_entry {
+ __u64 nr;
+ __u64 ip[]; /*
/proc/sys/kernel/perf_event_max_stack */
+};
struct bpf_perf_event_data {
bpf_user_pt_regs_t regs;
__u64 sample_period;
__u64 addr;
+ __bpf_md_ptr(struct perf_callchain_entry *, callchain);
};
#endif /* _UAPI__LINUX_BPF_PERF_EVENT_H__ */
diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index 4c3007f428b16..cb122e14dba38 100644
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -20,6 +20,7 @@
#include <linux/btf.h>
#include <linux/skmsg.h>
#include <linux/perf_event.h>
+#include <linux/trace_events.h>
#include <net/sock.h>
/* BTF (BPF Type Format) is the meta data format which describes
@@ -3673,6 +3674,10 @@ struct btf *btf_parse_vmlinux(void)
if (err < 0)
goto errout;
+ err = bpf_trace_init_btf_ids(btf);
+ if (err < 0)
+ goto errout;
+
bpf_struct_ops_init(btf, log);
init_btf_sock_ids(btf);
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index e0b7775039ab9..c014846c2723c 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -6,6 +6,7 @@
#include <linux/types.h>
#include <linux/slab.h>
#include <linux/bpf.h>
+#include <linux/btf.h>
#include <linux/bpf_perf_event.h>
#include <linux/filter.h>
#include <linux/uaccess.h>
@@ -31,6 +32,20 @@ struct bpf_trace_module {
static LIST_HEAD(bpf_trace_modules);
static DEFINE_MUTEX(bpf_module_mutex);
+static u32 perf_callchain_entry_btf_id;
+
+int bpf_trace_init_btf_ids(struct btf *btf)
+{
+ s32 type_id;
+
+ type_id = btf_find_by_name_kind(btf, "perf_callchain_entry",
+ BTF_KIND_STRUCT);
+ if (type_id < 0)
+ return -EINVAL;
+ perf_callchain_entry_btf_id = type_id;
+ return 0;
+}
+
static struct bpf_raw_event_map *bpf_get_raw_tracepoint_module(const char
*name)
{
struct bpf_raw_event_map *btp, *ret = NULL;
@@ -1650,6 +1665,10 @@ static bool pe_prog_is_valid_access(int off, int size,
enum bpf_access_type type
if (!bpf_ctx_narrow_access_ok(off, size, size_u64))
return false;
break;
+ case bpf_ctx_range(struct bpf_perf_event_data, callchain):
+ info->reg_type = PTR_TO_BTF_ID;
+ info->btf_id = perf_callchain_entry_btf_id;
+ break;
default:
if (size != sizeof(long))
return false;
@@ -1682,6 +1701,14 @@ static u32 pe_prog_convert_ctx_access(enum
bpf_access_type type,
bpf_target_off(struct perf_sample_data,
addr, 8,
target_size));
break;
+ case offsetof(struct bpf_perf_event_data, callchain):
+ *insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct
bpf_perf_event_data_kern,
+ data), si->dst_reg,
si->src_reg,
+ offsetof(struct bpf_perf_event_data_kern,
data));
+ *insn++ = BPF_LDX_MEM(BPF_DW, si->dst_reg, si->dst_reg,
+ bpf_target_off(struct perf_sample_data,
callchain,
+ 8, target_size));
+ break;
default:
*insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct
bpf_perf_event_data_kern,
regs), si->dst_reg,
si->src_reg,
diff --git a/tools/include/uapi/linux/bpf_perf_event.h
b/tools/include/uapi/linux/bpf_perf_event.h
index 8f95303f9d807..40f4df80ab4fa 100644
--- a/tools/include/uapi/linux/bpf_perf_event.h
+++ b/tools/include/uapi/linux/bpf_perf_event.h
@@ -9,10 +9,18 @@
#define _UAPI__LINUX_BPF_PERF_EVENT_H__
#include <asm/bpf_perf_event.h>
+#include <linux/bpf.h>
+
+struct perf_callchain_entry {
+ __u64 nr;
+ __u64 ip[]; /*
/proc/sys/kernel/perf_event_max_stack */
+};
struct bpf_perf_event_data {
bpf_user_pt_regs_t regs;
__u64 sample_period;
+ __u64 addr;
+ __bpf_md_ptr(struct perf_callchain_entry *, callchain);
};
#endif /* _UAPI__LINUX_BPF_PERF_EVENT_H__ */
--
2.24.1
